Voltage Regulator Control Circuit for Variable Switching Regulator
The CA1523 monolithic silicon integrated circuit is a variable interval pulse regulator designed to provide the control circuitry for use in switching regulator circuits. It operates from to 15V. The regulator provides a single output drive capable 300mA source/200mA sink. The maximum operating frequency is better than 200kHz. An attractive feature of the CA1523 is that the timing capacitor charge and discharge current is set up externally via a single resistor. The ratio of charge to discharge current is internally set at a maximum to 1 allowing simultaneous change in output pulse width with increased frequency at higher load. The pulse width variation at higher frequencies effectively compensates for the losses in magnetics and thereby increases the power supply efficiency at higher load end by as much as 20 percent.Features
Operates to 200kHz Pins ESD Protected Remote ON/OFF Slow Start with Reset Overcurrent Sensing Lower Peak Currents than PWM Regulator - Less Prone to Magnetic SaturationPART NUMBER CA1523E TEMPERATURE RANGE to +70oC PACKAGE 14 Lead Plastic DIP
ERROR CURRENT SENSE GND RISE TIME OUTPUT GND OUTPUT VCC TIMING 13 ZENER 12 ON/OFF 11 OVER CURRENT 10 SLOW START 9 8 LOGIC OUTPUT NC
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 407-727-9207 | Copyright � Intersil Corporation 1999
DC Supply Voltage. 15V Supply Current |6(MAX), 1�s,1800pF Load. +300, -200mA Device Dissipation 70oC. 530mW Above = 70oC. Derate Linearly at 6.7mW/oC
Thermal Resistance JA Plastic DIP Package. 120oC/W Device Dissipation 70oC. 665mW Ambient Temperature Range Operating. to +70oC Storage. to +150oC Lead Temperature (During Soldering) At distance 1/16 � in. (1.59mm �0.79mm) from case for 10s Max. +265oC
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Electrical Specifications = +25oC, Refer to condition shown in test circuit; = 5.9V Unless Otherwise Specified
PARAMETERS POWER SUPPLY, VCC (PIN 7) Supply Voltage Supply Current Zener Voltage OUTPUT PULSE (PIN 6) Maximum Pulse Width Minimum Pulse Width Output High Voltage Output Low Voltage Rise Time Fall Time ERROR VOLTAGE RANGE (PIN 1) Error Voltage Reference 1 Adjust RT; Observe Pin 6 Min/Max Frequency Range 7.5 V Measured at 6V Threshold Level Measured at 6V Threshold Level = 0V Measured at 1.8V and 10V Threshold Levels Measured at 1.8V and 10V Threshold Levels 7 13 VCC mA V PIN TEST CONDITIONS MIN TYP MAX UNITS
CHARGE CURRENT (PIN 14) Charge Current Discharge Current Slow Start Discharge Current 14 Adjust RT, = 7.5V; Set = 0V, Then = 2.5V Adjust = 5.9V; Set = 5.5V, Then 5V Maintain = 5.5V Set = 5.5V, Measure I14 (Hi) Set = 4V, Measure I14 (Lo) Limits = I14 (Hi) - I14 (Lo) �A �A/V
LOGIC TESTS Discharge Voltage Output Inhibit Voltage Overcurrent Trip Voltage 7 11 Pin 1k to GND Increase V7 Until = 0V; Increase V11 Until 0.5V V
Other desirable features along with various circuit block function explanations are listed below. The Oscillator is a sawtooth generator whose charge (rise) cycle determines the output pulse width and discharge which is continuously variable from very low to maximum of ICHARGE. Charge ICHARGE = IO -IDISCHARGE giving to 1 pulse-width control Discharge IDISCHARGE = approximately IO to frequency control. Pulse Shaping: Applied to the oscillator output via RS Flip-Flop with parallel inhibit controlled by slow-start overcurrent sense, supply voltage monitor and ON/OFF functions. Pulse Rise Time: Modified to meet RFI requirements by external slow-down capacitor. Slow Start with Reset: Externally programmed against internal 3V reference. Reset is initiated upon Inhibit ensuring soft start at power up and restart. Over Current Sense: Internal stable thresholds of 1.2V. Supply Voltage Monitors: Locks out the drive until VSUPPLY has reached 8V-9V. ON/OFF: Activates regulator independent of raw DC. Error Amplifier: Compares output against a stable 6.8V internal reference and controls the discharge current sink on the timing capacitor. Band-Gap: Reference voltage (internal) provides temperature compensated 1.2V and 6.8V references. Separate GND: The power GND is separated from circuit ground for improved noise. ESD Protection: Pins are protected against ESD.
5V REF. Q HIGH CLOSES ~ IC/2 FOR S Q F/F R 4 RISE TIME 6 PULSE OUTPUT S Q F/F VCC 8.4V R OUTPUT GND 11 OVER CURRENT